ENT: Ear Problems 1 Flashcards
Remind yourself of where the following are on the pinna of the ear:
- Helix
- Antihelix
- Tragus
- Antitragus
- Lobule
- External auditory meatus
- Concha
Label the following diagram of ear, include:
- Ear canal
- Tympanic membrane
- Each of the ossicles
- Auditory (Eustachain) tube
- Round window
- Oval window
- Cochlea
- Semi-circular canals
- Vestibulocochlear nerve
Label the following diagram of the tympanic membrane, include:
- Cone of light
- Handle of malleus
- Umbo (tip of malleus)
- Pars tensa
- Pars flaccida
- Incus
- Annulus
- Short process of malleus
- Anterior fold
- Posterior fold
State some of the common hearing tests for adults and briefly describe what is involved in each
Pure tone audiometry= most common
What does pure tone audiometry involve?
Test hearing by playing variety of tones at different volumes. Aim is to establish the quietest volume at which the patient can hear each frequency (tone). E.g. 1000Hz will be played at various volumes until pt can just about hear the sound then mark on the graph
Briefly describe how pure tone audiometry is done
- Sound proof room
- Before test, examine ears for infection, foreign body or occluding wax
- Patient wears headphones to test air conduction, followed by a bone vibrator places on mastoid process to test bone conduction.
- Audiometer machine makes pure tone sounds at varying frequencies
How is air conduction measured in audiometry?
Wear headphones and audiometer produces sounds of varying frequnecies at different decibels
How is bone conduction measured in audiometry?
Vibrator placed on mastoid process
For an audiogram, discuss what:
- Is on the Y axis
- Is on the X axis
- What an X means
- What an O means
- What a ] means
- What a [ means
- Y axis is volume (decibels/dB)
- X axis is frequency (Hz)
- X= left sided air conduction
- O= right sided air conduction (HINT: think Oh right)
- ]= left sided bone conduction
- [= right sided bone conduction (HINT: think looks like the pt’s right ear, vice versa for left)
What decibel range is normal hearing?
All readings between 0-20dB
What is the pure tone threshold?
Lowest decibel hearing level (i.e. quietest sound) at which the patient detects the pure tone at least 50% of the time
Discuss how an audiogram will vary for sensorineural and conductive hearing loss
- Sensorineural: both air and bone conduction will be more than 20dB
- Conductive: bone conduction will be normal (0-20dB) and air conduction will be more than 20dB
Discuss what an audiogram would show in a patient with mixed hearing loss
Both air and bone conduction will be more than 20dB however there will be a difference of more than 15dB between the two (in which bone conduction > air conduction)
What is masking?
Masking is when you present a sound to the non-test ear (masking noise) to prevent it from detecting the sound being presented to the test ear.
What would you see on the audiogram of someone with noise-induced hearing loss?
Boiler’s notch
What type of hearing loss does this audiogram suggest?
Presbyacusis (showing bilateral high frequency hearing loss)
What type of hearing loss is represented by each of the lines on the audiogram?
What is the difference between conductive and sensorineural hearing loss?
- Conductive: problem with sound travelling from external environment to inner ear; problem with external or middle ear
- Sensorineural: problem with sensory system or vestibulocochlear nerve in inner ear
Hearing loss may be associated with other symptoms; state some examples
- Tinnitus
- Vertigo
- Pain (indicate infection)
- Discharge (indicate middle or outer ear)
- Neurological symptoms
State some causes of sensorineural hearing loss in adults
- Sudden onset sensorineural hearing loss (<72hrs)
- Presbyacusis
- Noise exposure
- Ménière’s disease
- Labyrinthitis
- Acoustic neuroma
- Neurological conditions (e.g., stroke, multiple sclerosis or brain tumours)
- Infections (e.g., meningitis)
- Medications
- Loop diuretics (e.g. furosemide)
- Aminoglycosides (e.g. gentamicin)
- Chemotherapy drugs (e.g. cisplatin)
State some causes of conductive hearing loss in adults
- Blockage in ear canal (e.g. wax)
- Infection (e.g. otitis media or otitis externa)
- Effusion in middle ear
- Eustachian tube dysfunction
- Perforated tympanic membrane
- Otosclerosis
- Cholesteatoma
- Exostoses
- Tumour
For Weber’s remind yourself:
- What tuning fork is used
- How to perform
- Normal result
- Result in sensorineural hearing loss
- Result in conductive hearing loss
- 512Hz
- Strike tuning fork to make it vibrate, place in centre of pt’s forehead, ask pt if they can hear sound and which ear is loudest in or if the same
- Normal= hears sound equally in both ears
- Sensorineural= sound louder in normal ear
- Conductive= sound louder in affected ear
For Rinne’s, remind yourself:
- What tuning fork is used
- How to perform
- Normal result/Rinne’s positive
- Abnormal result/Rinne’s negative
- 512Hz
- Strike turning fork to make it vibrate, place flat end on mastoid process, tell pt to tell you when they can no longer hear the humming noise, when they can no longer hear it remove the tuning fork that is still vibrating and hover it 1cm from the same ear, ask if they can still hear the humming noise
- Normal/Rinne’s positive= pt can hear sound again when move tuning fork next to the ear (air>bone)
- Abnormal/Rinne’s negative= sound not heard after moving tuning fork next to hear (bone>air)
What is sudden sensorineural hearing loss? **HINT: rule of 3
Is it permanent?
- Hearing loss of 30dB or greater over at least three contiguous audiometric frequencies occurring within <72hrs for which no conductive cause can be found; usually unilateral
- Hearing loss may resolve over days to weeks or may be permanent
**NOTE: causes of rapid onset hearing loss that are due to conductive problems (and hence not SSHL) include ear wax (or other blockage), infection, middle ear effusion, eustachian tube dysfunction, perforated tympanic membrane
A cause is identified for most cases of sudden sensorineural hearing loss; true or false?
FALSE; 90% cases are idiopathic. Other possible causes include:
- Infection (e.g., meningitis, HIV and mumps)
- Ménière’s disease
- Ototoxic medications
- Multiple sclerosis
- Migraine
- Stroke
- Acoustic neuroma
- Cogan’s syndrome (a rare autoimmune condition causing inflammation of the eyes and inner ear)
If someone presents with sudden sensorineural hearing loss within 30 days of onset what should you do?
Immediate (within 24hrs) referral to ENT for assessment
What investigations will be done in secondary care for sudden onset sensorineural hearing loss?
- Audiometry: required for diagnosis- GOLD STANDARD (need a l_oss of at least 30 decibels in three consecutive frequencies_)
- MRI or CT head: if considering acoustic neuroma or stroke
Discuss the management of sudden onset sensorineural hearing loss
Immediate (within 24hrs) referral to ENT if presented within 30 days of onset. ENT can then organise investigations and oversee treatment and follow patient up.
-
Idiopathic: steroids (either PO or intra-tympanic)
- Most cases are started on PO high dose steroids in primary care whilst ENT organise urgent pure tone audiometry
- Other cause identified: treat the cause
***NOTE: intra-tympanic injections are injections through tympanic membrane
How is presbycusis diagnosed?
Audiometry
- Sensorineural
- Normal/near-normal hearing at low frequencies
- Poor hearing at high frequencies
What might you see on otoscopy of pts with otosclerosis?
Schwartz sign/flamingo tinge (red tinge to tympanic membrane on otoscopy)
Explain what tympanometry involves
Tympanometry involves:
- Inserting a device into the external auditory canal (ear canal)
- Creating different air pressures in the canal
- Sending a sound in the direction of the tympanic membrane
- Measuring the amount of sound reflected back off the tympanic membrane
- Plotting a tympanogram (graph) of the sound absorbed (admittance) at different air pressures
The amount of sound absorbed by the tympanic membrane and middle ear (not reflected back to the device) is known as the admittance.
Normally, sound is absorbed best when the air pressure in the ear canal matches the ambient air pressure. The ambient air pressure is equal to the middle ear pressure in healthy ears.
When there is Eustachian tube dysfunction, the air pressure in the middle ear may be lower than the ambient air pressure because new air cannot get in through the tympanic membrane to equalise the pressures. As a result, the tympanogram will show a peak admittance (most sound absorbed) with negative ear canal pressures.
What is an acoustic neuroma?
State 2 other names for an acoustic neuroma
- Benign tumours of Schwann cells surrounding the vestibular component (or of all parts???? ASK) of the vestibulocochlear nerve
- Alternative names:
- Vestibular schwannoma
- Cerebellopontine angle tumours (due to location)
Describe typical presentation of acoustic neuromas
Typically aged 40-60yrs presenting with gradual onset of:
- Unilateral sensorineural hearing loss (unless bilateral acoustic neuroma in which case bilateral)
- Unilateral tinnitus
- Dizziness or imbalance
- Sensation of fullness in ear
- Absence of corneal reflex
- May be associated with facial nerve palsy (if large enough to compress facial nerve)
For each of the symptoms of acoustic neuroma explain, in terms of structures affected, why pts get each of these symptoms
- CNVIII: sensorineural hearing loss, tinnitus, vertigo
- CNV: absent corneal reflex (remember trigeminal nerve responsible for facial sensation)
- CNVII: facial palsy
Describe pathophysiology of cholesteatomas
Not fully understood but think that Eustachian tube dysfunction causes negative pressure in middle ear which causes part of tympanic membrane (usually pars flaccida) to retract into middle ear. Squamous epithelial cells, that originate from outer surface tympanic membrane, continue to grow and proliferate into surrounding space and structures causing destruction (can damage tissue, nerves and bones)
What might you see on otoscopy in pt with cholesteatoma?
- Presence of a deep retraction pocket, with or without granulation tissue and skin debris.
- Crust or keratin in the upper part of the tympanic membrane.
- The tympanic membrane may be perforated
What does a congenital cholesteatoma look like on otoscopy?
White mass behind an intact tympanic membrane, in a person with no prior history of ear discharge, tympanic membrane perforation, or surgical procedures on the ear.
For an auricular haematoma, discuss:
- What it is (being specific about where blood accumulates)
- Common cause
- Management
- Complications
- Blood and serum accumulates between the cartilage and overlying perichondrium in the ear (most commonly affects helical rim of pinna)
- Trauma
- Cartilage is avascular and gets it blood supply from perichondrium hence separation of these layers results in avascular necrosis of cartilage
-
Same day referral to ENT for assessment & management
- Aspiration
- Incision & drainage (shown to be superior)
- Complication: cauliflower ear deformity (get new asymmetrical cartilage development)
State some different types of hearing aids
Briefly outline how bone conduction implants work
- External sound processor converts the sound picked up by its microphone into vibrations. The sound processor then transmits the vibrations through the bones of the skull to the cochlear of the inner ear. The inner ear then converts these (sound) vibrations into electrical signals that the brain interprets as sound.
- Bypasses external and middle ear
- Can be transcutaneous (magnet) or percutaneous (shown in image)
Briefly outline how cochlear implants work
- Sound picked up by microphone worn on or near ear
- Sound waves then converted into digital signal
- Wire delivers signals from to electrodes that have been surgically implanted in cochlear
- Electrode receives signal and creates and sends electric impulses directly to cochlear nerve
Briefly outline how brainstem implants work
Who are they often given to?
- Sound is picked up by microphones in the external speech processor and converts this into digital signals. Digital signals delivered to electrodes on cochlear nucleus producing stimulation that can be interpreted as sound in auditory cortex of brain
- Patients with neurofibromatosis type II (these pts often have bilateral acoustic neuromas; surgery for these may involve injury to CNVIII)
